Many of today's computing systems are powered by power sources that are not always reliable. In some instances, a power supply of a computing system, like those found in a typical data center, may periodically transition to auxiliary power sources when primary power sources experience disruptions. For example, in a typical data center, computing systems are generally powered by mains power but may periodically transition to auxiliary generators during mains-power disruptions. After primary power sources are restored, an additional transition generally must occur back to the primary power sources from auxiliary power sources. During transitions between primary and auxiliary power sources, a power supply may not receive power from either power source. While transitions between primary and auxiliary power sources may be quick, commonly occurring in seconds or a few minutes, these transitions are typically not instantaneous.
Because of the non-instantaneous transitions between primary and auxiliary power sources, typical computer-system power supplies generally rely on backup batteries to supply power during the transitions. Unfortunately, most batteries have limited lifespans, which are generally far shorter than the lifespans of the power supplies to which they supply backup power. As a result, backup batteries may limit the lifespans of the power supplies or must be replaced to ensure that the power supplies deliver uninterrupted power. Additionally, to ensure that backup batteries of power supplies perform their designed role, backup batteries may need to be replaced long before the ends of their expected lifespans.
A typical battery charger may charge a depleted rechargeable battery by applying a constant current to the rechargeable battery until the voltage of the rechargeable battery reaches a predetermined threshold, after which the battery charger may apply a constant voltage to the rechargeable battery until the rechargeable battery is fully charged, which may maximize the available charge of the rechargeable battery and/or the amount of time between a full charge of the rechargeable battery and a full discharge of the rechargeable battery. Unfortunately, this method of charging batteries may unnecessarily reduce the lifespan of batteries in certain circumstances. For example in some situations, charging a rechargeable battery using a constant current or voltage may (1) cause the rechargeable battery to heat up, which may reduce the lifespan of the rechargeable battery over time, and/or (2) prevent ions of the rechargeable battery from properly diffusing into the negative electrode of the rechargeable battery, which may reduce the capacity and/or the lifespan of the rechargeable battery as it ages. The instant disclosure, therefore, identifies and addresses a need for apparatus, systems, and methods that prolong the expected lifespans of batteries, especially backup batteries of power supplies.